In our clinical work, we often find a situation where misfortune befalls the same family one after another. The husband has just gotten bowel cancer, and the wife has gotten breast cancer; soon, the children also suffer from incurable diseases one after another. Although we cannot rule out familial genetic factors, we cannot ignore the fact that poor family environment (such as poor lifestyle, family hygiene and family relationship) can also be a cancer-causing factor. Poor lifestyle About 70% of cancers are related to it. Lifestyle is family in nature and often family members influence each other. Some people are accustomed to eating salty, smoked, pickled and grilled foods, which are likely to cause stomach cancer. Pickled foods contain carcinogenic substances nitrosamines, and polycyclic aromatic hydrocarbons contained in smoked foods such as bacon and preserved fish are also carcinogens. In addition, the long-term intake of high-fat diet can cause intestinal cancer and predispose women to breast cancer. Studies have confirmed that nicotine contained in tobacco is a single active and fast-acting carcinogen. Smoking also produces carbon monoxide, nitrosamines, nitrogen oxides, polycyclic aromatic hydrocarbons, benzo(a)pyrene, formaldehyde, hydrogen cyanide, nitrogen oxides and other toxic substances that can victimize other family members. In a closed room, if there are two or three burning cigarettes, passive smokers are often the first to get sick due to their lower immunity to cigarette toxicity. This is an important reason why some families have multiple cancer cases. Alcohol has become another killer after cigarettes in today’s society. Long-term excessive alcohol consumption, especially strong alcohol, can cause oral cancer, laryngeal cancer and esophageal cancer, as well as liver toxicity, which can lead to liver cirrhosis and liver cancer. Another harmful effect of excessive alcohol consumption is to suppress the body’s immune system, reducing the body’s immune function and making people more susceptible to cancer or other diseases. If a person drinks and smokes, the chances of cancer increase exponentially when the two work together. Poor home hygiene Over-decoration will make indoor toxic chemicals (such as formaldehyde, radon gas, etc.) significantly exceed the standard. Cleaners, paints and coatings used daily also contain toxic chemicals. Indoor darkness and humidity will make mold proliferate and cause mold in clothes and food, while aflatoxin in food is also a strong carcinogen. Tension in family relationship Tension in interpersonal relationship and long-term psychological depression can lower the immunity of human body, which can lead to cancer. A survey found that women with unfortunate marital history and marital discord have a higher risk of breast cancer. To sum up, creating a scientific and civilized family environment is the fundamental guarantee for disease prevention. Therefore, we advocate that cancer prevention and health care should start from family, from self and from now on.